Ion chromatography is a relatively new type of ion exchange chromatographic technology. H. Small etc. of the Dow Chemical Co., U.S.A., published an article "Novel Ion Exchange Chromatographic Method Using Conductimetric Detection" in Anal. Chem., Vol. 47, 1975, introducing ion chromatography for the first time and embodying an ion chromatograph with a restraint or suppressor column, wherein a low volume and high performance ion exchange agent is used as the packing of the separation column. The detector is a conductivity gauge, and a relatively high pressure Milton-Roy pump is used for transporting the eluent. Disturbance of the eluent conductance at the conductivity detector may be reduced, however, by inserting a restraint/column. D. T. Gjerde and J. S. Fritz et al. published their article "Anion Chromatography with Low-Conductivity Eluent" in J. Chromatography Vol. 186, 1979. They also produced an ion chromatograph without a restraint column but still required a relatively high pressure Milton-Roy pump (200-450 p.s.i.--or 14-31 kg/cm.sup.2) to transport the eluent, and employed a conductivity gauge as the detector.
At present, such prior ion chromatographs for the analysis of cations, however, have the following disadvantages:
(1) High pressure requirement (said 14-31 kg/cm.sup.2) for joints, pipes and valves.
(2) Leakage often takes place.
(3) Complicated structure.
(4) High cost--about $40,000-$100,000 per set.